Process of making anhydrous barium hydroxid.



UNITED STA'l B l S Ji}EENT OFFICE.

CHARLES ROLLIN, or NEWCASTLE-UPON-TYNE, ENGLAND, ASSIGNOR ro HIMSELF.AND HEDWORTH 'BARIUM COMPANY LIMITED, or. NEWCASTLE-UPON-TYNE,

ENGLAND.

PROCESS OF MAKING A NI-IYDROUS B'ARIUM HYDROXID.

Specification of Letters Patent.

Patented Nov. 8, 1910.

No Drawing. Original application filed June 3, 1909, Serial No. 499,922;Divided and this application filed February 23, 1910. sci-mp0. 545,387,.

To all whom it'may conccrn:

Be it known that I, Crrannns Roman, B. So, F. G. S., a subject of theKing of Great Britain andIreland, residingat N ewcastlc upon-Tyne,England, have invented Improvements in or Relating to the ManufactureofAnhydrous Barium Hydroxid, of.

Serial No. 499,922 filed by me, the present being a division thereof, itis essential that the barium oxid, formed as an intermediate product,shall not only be practically pure, but that it shall be in a porouscondition, so .as to expose sufficient surface to the oxidizinginfluence used for its complete conversion into the peroxid.

If it be attempted to driveotf the Water of crystallization fromcommercially pure crystallized barium hydroxid by heat, under ordinaryatmospheric pressure, it is necessary,

in order to complete the action on the large scale, to employ a hightemperature with the result that the hydroxid, while fused in its ownwater of crystallization, exerts so strong a solvent action on thematerials with which it comes in contact that, by the time the Water ofcrystallization is driven off, not

only is the anhydrous hydroxid very dense,

but it contains impurities which detract from the value of the peroxidmade from it.

No method has however been ever suggested by which an anhydrousamorphous bariumhydroxid could be produced on the la'r e scale. Tomention only one of the di culties of effecting practically completevelimination of the water, there is the tende'ncy forthe outside of thematerial under treatment to be more or less freed from v water longbefore the inside, can be acted 'upon and the hard outer layer therebyproduced acts to prevent the complete removal of the water from theinner portion. Thisdisadvantage can only be avoided-by taking specialprecautions such as herein, set forth;

Now the present invention has for-object to produce ina simple andadvantageous manner and on an industrial-scale, practically pureanhydrous and amorphous barium hydroxid of uniform quality and in a.sufficiently porouscondition 'to admit of its ready conversion intobarium oxid. For this purpose, commercially pure crystalline bariumhydroxid is heated at a comparatively low temperature in a partialvacuum in suchmanner that sudden rise in tern erature of any partthereof is avoided and the heat gradually-transmitted throughout themass and raised to the necessary'degree. As an example,-if purecrystallized barium hydroxid, containing eight molecules of water ofcrystallization, be ver slowly and uniformly heated in a partia vacuumin which the pressure does not much exceed that cor.- responding to oneinch of mercury, correspondingsay to about 29 inches) of vacuum,practically the whole of the water of crystallization can be driven ofiat'a temperature below 200 C. (two hundred degrees centigrade) and asoft White orous mass of amorphous barium hydroxid obtained in whichonly a very small proportion of the original waterof crystallizationwill remain, and which, from its physical condition, is well adapted forconversion into barium oxid.' Even when crystallized barium hydroxid isheated in a' (twenty nine een to twenty inches of vacuum at atemperature of from about 160 to 200 0. (one hundred and sixty .to twohundred degrees centigrade'), a, soft white porous mass of amorphousbarium hydroxid has been obtained containing only about 25% to .5%(decimal two five to decimal five per cent.) of its weight of theoriginal water of crystallization.

In another example the process can be conducted as last above desclibedbut with a temperature range of from 100 t0/200" C. (one hundred to twohundred degrees centigrade) The, heating under vacuum may c0nvel1-.iently be carried out in a vessel formed of steel heated externally, asby a fire, flue gases, or superheated steam, the vessel having a flat orextended bottom over which the crystallindbarium hydroxid to be treatedis' spread in a comparatively thinlayer, having a, depth of say forexample, about two to three inches.

' process consisting in slowly a vacuum.

With a layer ,of barium hydroxid of this thickness and the degree ofheat and vacuum last above mentioned, satisfactory results. have beenobtained by ing for about two days.

continuing the heat- The duration of the operation may however varyaccording to various circumstances, such as the thicknessof the la er ofbarium hydroxid used, the degree of lieat employed, and the degree ofvacuum maintained, provided adequate.

precautions, as hereinabove indicated, are taken to avoid suddentemperature changes or irregularity of treatment.

What I claim is,:'

1. A process for producing anhydrous barium hydroxid in an amorphouscondition from crystallized barium ydroxid, said and uniformly heatingthe crystallized barium hydroxid in comparatively thin layers in apartial 2. A process for iiroducing anhydrous amorphous, barium hydroxidfrom crystallized barium hydroxid, said rocess consisting .in slowly anduniformy heating the crystallized barium 'hydroxid' in comparaamor ghousbarium h droxid tively thin layers in a partial vacuum at acomparatively low temperature.

3. A process for producing anhydrous rom crystallized arium hydroxi,said rocess consisting in slowly and uniformi heating the crystallizedbarium hydroxi in comparatively thin layers in apartial vacuumatatemperature below two hundred degrees centigrade. Y

4. A process for producin anhydrous. amor hous barium h droxid romcrystallized arium hydroxi said rocess consisting in slowly and uniformiheating the crystallized barium hydroxi in comparatively thin layers ina partial vacuum corresponding to from eighteen .to twent inches ofvacuum at a temperature les's tian two hundred degrees cent-lgrade butnot less than one hundred degrees centigrade.

Signed at Newcastle-upon-Tyne, Englanch this ninth day of February 1910.

. CHARLES ROLLIN.

Witnesses:

ALnxR. WARDLAW, H. NIXON.

